JPH0520984Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] This invention relates to a device for measuring the amount of evaporation of liquefied gas, and more specifically, it measures the amount of evaporation of liquid helium etc. stored in a low-temperature container using a flowmeter. The present invention relates to an apparatus for measuring the amount of evaporation of liquefied gas.

[Conventional technology]

Figure 2 shows Advances in Cryogenic Engineering (Advances in Cryogenic Engineering).
Cryogenic Engineering) Volume 25, Page 492, No. 3
This is a portion of the conventional liquid helium evaporation measurement device shown in the figure, which is related to the present invention. In the figure,
The cryogenic device 10 includes a liquid nitrogen tank 2 in a vacuum tank 1;
A liquid helium inner tank 3 and a liquid helium inner tank 4 are housed. 5 is a sample on the low temperature side, and 6 is a sample on the high temperature side. A flow meter 7 is connected to the liquid helium inner tank 4.

With the above configuration, liquid nitrogen is stored in the liquid nitrogen tank 2, and is cooled to about 78K, and the high temperature sample 6 is also maintained at the same temperature. Also,
Liquid helium is stored in the liquid helium inner tank 4, and is cooled to about 4.2K, and the low temperature sample 5 is also maintained at the same temperature. Liquid helium is also stored in the liquid helium tank 3, which is also cooled to about 4.2K.

In the above equipment configuration and temperature configuration, the amount of evaporation of the liquid helium stored in the liquid helium inner tank 4 is limited to the amount of evaporation of the liquid helium stored in the liquid helium inner tank 4, since the inside of the vacuum tank 1 is under an ultra-high vacuum of 1 × 10 ^-7 Torr or less. 6 to the low temperature sample 5. That is, this is to determine the thermal emissivity between samples, and the amount of evaporation of liquid helium is measured by the flowmeter 7, and the discharged gas after measurement is released into atmospheric pressure.

[Problem that the invention attempts to solve]

In the conventional liquefied gas evaporation measuring device as described above, the discharge side of the flowmeter is open to the atmosphere, so the measured values are disturbed by changes in atmospheric pressure, causing errors. In particular, when the amount of evaporation is small, in addition to the above-mentioned errors, changes in atmospheric pressure are also affected by changes in the flow rate itself since changes in back pressure occur, resulting in a fatal error in the measured values.

This invention was made in order to solve the above-mentioned problems, and the purpose is to alleviate the influence of changes in atmospheric pressure and to obtain a device for measuring the amount of evaporation of liquefied gas with high accuracy.

[Means for solving problems]

The liquefied gas evaporation measurement device according to this invention is
The discharge port of the flowmeter is located below the bottom of the liquid helium tank in a liquid whose top surface is in contact with the atmosphere.

[Effect]

In this invention, the pressure of the liquid helium inner tank has a position head relative to atmospheric pressure that corresponds to the depth at which the discharge port is located and the liquid, making it less susceptible to changes in atmospheric pressure.

〔Example〕

FIG. 1 shows an embodiment of this invention, in which a flowmeter 7
The discharge port 7a is located in the liquid 9 contained in the container 8. The discharge port 7a is located below the bottom surface of the liquid helium inner tank 4.

In addition, the same reference numerals as in FIG. 2 indicate the same parts.

With the above configuration, the evaporation phenomenon and amount of liquid helium from the liquid helium inner tank 4 can be measured by the flowmeter 7.
The measurement is the same as the conventional device. However, the pressure inside the liquid helium tank 4 is higher than the atmospheric pressure by the amount of the liquid 9 provided with the evaporated gas discharge port 7a and the position head corresponding to the depth. Therefore, even if the amount of evaporation from the liquid helium inner tank 4 is small, the influence of changes in atmospheric pressure can be alleviated, making it possible to perform accurate measurements.

Note that the liquid 9 may be anything, such as water or oil, as long as it does not evaporate much at room temperature.

[Effect of idea]

As is clear from the above explanation, this idea
The discharge port of the flowmeter is located below the bottom of the liquid helium tank in a liquid whose top surface is in contact with the atmosphere, which reduces the effects of atmospheric pressure changes on the amount of evaporation, and improves accuracy even with regard to minute amounts of evaporation. This has the effect of obtaining good measured values.

[Brief explanation of the drawing]

Figure 1 is a front sectional view of one embodiment of this invention, Figure 2 is a front sectional view of an embodiment of this invention.
The figure is a front sectional view of a conventional liquefied gas evaporation measurement device. 4...Liquid helium inner tank (low temperature container), 7 is a flow meter, 7a is a discharge port, 9 is a liquid for applying head.
In each figure, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Scope of utility model registration request] In a liquefied gas evaporation measurement device that measures the evaporation amount of natural evaporation gas of liquid helium stored in a liquid helium inner tank using a flowmeter, the discharge port of the flowmeter is connected to the liquid where the upper surface is in contact with the atmosphere. A device for measuring the amount of evaporation of liquefied gas, characterized in that it is located below the bottom of a helium inner tank.